240 Annals Entomological Society of America [Vol. XIV, 
by the observer from a distance, such groups of insects appear 
as dark patches on the surface of the stream, rising and falling 
with the movements of the water. It was interesting to me to 
find in a paper by de la Torre-Bueno (1911), who is a very 
accurate observer, certain records of behavior of a similar 
character with respect to a member of the same family, Gerrida, 
to which Gerris remigis belongs. He refers to Metrobates 
hesperius Uhler, of the tribe Halobatini, placed in the sub- 
family Gerrine. The following quotation is taken from his 
paper (1911, pp. 249-250): 
This is a species which, like most of the other members of the tribe, 
is lacustrine to a very great extent, and it may be seen congregated in 
large patches of blackness on the smooth waters of our lakes, or perhaps 
in the wide reaches of slow moving streams. It is a very active species. 
. . . It commonly occurs in the apterous, but the winged form seems 
not rare under favorable conditions. 
Fig. 5. Detail of large pool at headwaters of small brook, with current flowing 
through it—looking down stream—near Syracuse, New York— spring. 
Hundreds of water-striders, Gerris remigis Say, form large groups on surface 
of pool (a), grouping themselves near overhanging banks, especially when 
wind is off shore; also found crawling onto and into the interstices of 
fallen, dead tree, separating pool into two parts, and forming groups near it. 
Both alate and apterous water-striders hibernate in interstices of overhang- 
ing shore (c) and among vegetation and dead leaves (b), in close proximity 
to pool. (Reproduced from the American Naturalist.) 
